1. Technical Field
This invention relates to a chain saw cutting chain safety stop that is operatively connected to an existing rotatively mounted front handle of a chain saw and is independently actuated by the rotative action of such front handle to stop the cutting chain.
2. Background Art
The prior art, U.S. Pat. No. 3,664,390 discloses safety means for power driven chain saws; U.S. Pat. No. 3,776,331 discloses a brake device for power saws; U.S. Pat. No. 3,934,345 discloses a snap-acting over-center chain saw safety brake and method of operation thereof; U.S. Pat. No. 3,964,333 discloses a safety braking mechanism for a portable chain saw; U.S. Pat. No. 3,991,469 discloses a safety braking mechanism for a portable chain saw; U.S. Pat. No. 3,991,864 discloses a motor saw, especially motor chain saw; U.S. Pat. No. 3,992,779 discloses a chain brake for chain saws; U.S. Pat. No. 4,026,392 discloses a snap-acting over-center chain saw safety brake and method of operation thereof; U.S. Pat. No. 4,121,339 discloses a safety brake mechanism for chain saws; U.S. Pat. No. 4,156,477 discloses a braking system of a chain saw; U.S. Pat. No. 4,324,045 discloses a motor chain saw with dynamic safety braking device; U.S. Pat. No. 4,334,357 discloses a safety braking apparatus for a portable chain saw; U.S. Pat. No. 4,426,563 discloses a chain saw safety switch.
The following discussion focuses on the problems inherent in the prior art and how this invention contributes to the solution of such prior art problems.
"Kick-Back" means that the outgoing run of the cutting chain is jammed, caught or otherwise encounters resistance thereby causing the cutter bar, mounting such cutting chain to be thrown back towards the operator, causing serious injury or even death. For example, a right handed operator grasps and holds the chain saw with his left hand holding a cross-wise, gripping front handle and his right hand holding a rear control handle aligned with the front to rear longitudinal axis of such chain saw. When "Kick-Back" occurs, the operator's left hand, holding such cross-wise front handle rotates on such front handle as the chain saw rotates towards him, thus sending the cutter bar in his direction. In certain circumstances, the operator of a chain saw may loose his balance and fall on his running chain saw, the result being very serious injury or possibly even death.
The prior art; U.S. Pat. No. 3,664,390; U.S. Pat. No. 3,776,331; U.S. Pat. No. 3,934,345; U.S. Pat. No. 3,964,333; U.S. Pat. No. 3,991,469; U.S. Pat. No. 3,991,864; U.S. Pat. No. 3,992,779; U.S. Pat. No. 4,026,392; U.S. Pat. No. 4,121,339; U.S. Pat. No. 4,156,477; U.S. Pat. No. 4,324,045 and U.S. Pat. No. 4,334,357 relate to chain stopping devices to prevent injuries related to "Kick-Back". The drawback of said proposals being the loss of time between the start of the "Kick-Back" or "Throw" of the cutter bar and the actuation of said chain stopping devices. Also, these proposals are intended for the occurance known as "Kick-Back", but are not designed to prevent injury to the operator in other accident situations, such as an operator falling on his running chain saw. U.S. Pat. No. 4,426,563 relates to a hand held, rotatively mounted front handle of a chain saw to shut off the ignition to the power source of such chain saw, either automatically, as in "Kick-Back" or at the operator's option in other accident situations. Although this proposal puts control to shut off the power source of the saw in the operator's hand, which is holding the front handle, it is understood that even though the driving force to the cutting chain is removed, said cutting chain may continue to freely rotate for a short period of time as it comes to a stop. In this situation, it is possible for the operator to come in contact with the cutting chain as it is coming to a stop.
It is the object of this invention to contribute to the solution of such prior-art problems by providing a safety chain stopping device that is operatively connected to an existing rotatively mounted front handle of a chain saw. Said chain stopping device being actuated to quickly stop the cutting chain by the rotative action of said rotatively mounted front handle. It is understood that, since this invention is actuated to stop the cutting chain by the action of the front handle, while being held by the operator, said actuation takes place instantly. It is the further object of this invention to provide a means of quickly stopping the cutting chain of a chain saw that is uncomplicated in design and can be adapted to either gasoline engine powered chain saws or electric motor powered chain saws. After the safety stop has been actuated to its chain stopping position, it must be reset to its "Run" position before the cutting chain will freely rotate.
It is another object of the present invention to provide the operator with a great amount of control to quickly stop the cutting chain in various accident situations. Present invention is actuated automatically by the rotatively mounted front handle when kick-back causes the front handle to rotate in the operator's hand or by the operator manually rotating the front handle at his option.